Respiratory apparatus



Nov. 26, 1957 a. B. HOLMES RESPIRATORY APPARATUS Filed April 25. 1952 3 Sheets-Sheet 1 v INVENTORA BRADFORD B. HOLMES HTTOR EV Nov. 26, 1957 5.5, HOLMES 2,814,291

RESPIRATORY APPARATUS 7 Filed April 25. 1952 3 Sheets-Sheet 2 INVENTOR. BRADFORD B HOLMES BY R 9a yaw,

' HTTOIQIVEY Nov. 26, 1957 B. B. HOLMES RESPIRATORY APPARATUS 3 Sheets-Sheet 3 Filed. April 25. 1952 FIG. 5

INVENTOR. BRADFORD B. HOLMES ATTORNEY United States Patent 2,814,291 RESPIRATORY APPARATUS Bradford B. Holmes, New York, N. Y., assignor to Bendix Aviation Corporation, Teterboro, N. J a corporation of Delaware Application April 25, 1952, Serial No. 284,333

' 9 Claims. (Cl. 128-142) This invention in general relates to respiratory apparatus and more particularly to a novel demand regulator for controlling the delivery of respirant gases to an aviators breathing mask.

. With the advent of prolonged high altitude flights it has become common practice to equip the aviator with a breathing mask to which is supplied the oxygen required to sustain life at high altitude. The oxygen supply system usually comprises one or more bottles, or flasks, of compressed oxygen that are carried by the aircraft, and a demand regulator that is operated by the breathing of the aviator to control the quantity and pressure of the oxygen delivered from the bottles to the mask.

The present invention contemplates and has for one of its objects, the provision of a novel demand regulator that is constructed and arranged to be carried by, and form 'a part of an aviators breathing mask and which includes a novel demand valve, that is operated in response to the aviators breathing to regulate the quantity and pressure of oxygen supplied to the breathing mask.

A further object of the instant invention is to conserve the supply of oxygen available for use by the aviator and to that end the novel demand regulator contemplated herein embodies means whereby ambient air may be supplied tothe breathing mask. Thus, at altitudes where the ambient air contains suificient oxygen to maintain normal human efliciency, for example, at altitudes below 10,000 feet, the regulator is adjustable to permit the aviator to breathe the ambient air.

The present invention also has for one of its objects the provision of means for preventing the dilution of the oxygen supplied to the breathing mask. To this end, the instant demand regulator embodies novel means whereby, when oxygen is supplied to the mask, the demand valve is actuated so as to maintain within the mask a slight positive pressure relative to ambient atmospheric pres-v sure, to thereby prevent any inward leakage of ambient air into the mask and the consequent dilution of the oxygen supplied thereto.

A still further object of the instant invention is to provide means whereby at relatively high altitudes, for example, in excess of 40,000 feet, the oxygen supplied to the mask may be forced into the lungs of the aviator. Therefore, the novel demand regulator contemplated herein embodies means that is automatically responsive to the ambient atmospheric pressure at a predetermined altitude to actuate the demand valve so as to build up the pressure of the oxygen within the regulator and mask to a value where the oxygen will be forced into the lugs of the aviator.

To provide means for conserving the supply of oxygen sponsive means to thereby discontinue the high pressure of oxygen within the mask.

The foregoing and other objects and advantages of the instant invention will appear more fully hereinafter ii ice from a consideration of the detailed description which follows, taken together with the accompanying drawings wherein one embodiment of the invention is illustrated by way of example. It is to be expressly understood, however, that the drawings are for the purpose of illustration only, and are not to be construed as defining the limits of the invention.

Referring to the drawings wherein like reference characters designate like parts throughout the various views:

Fig. 1 is a schematic illustration, partially in section, showing the novel regulator contemplated herein asso ciated with an aviators breathing mask and connected to a source of oxygen;

Fig. 2 is a longitudinal section through the regulator;

Fig. 3 is an end view of the regulator as seen from the interior of the mask;

Fig. 4 is an elevational view of the regulator, partially in section, with the cover and diaphragm removed;

Fig. 5 is an elevational view of the inside of the cover; and

Fig. 6is a fragmentary view, partially in section showing the mounting of the primary and secondary levers to the cover.

Referring now to the drawing and particularly Fig. 1, the reference character 10 indicates a breathing mask of the type that is adapted to be secured to the face of an aviator. The novel demand regulator contemplated herein, and indicated generally by the reference character 11, includes a casing 12 having a peripheral groove 13 whereby regulator 11 is mounted within a suitable opening formed in mask 10. When so mounted, regulator 11 is disposed in front of the mouth and nose of the aviators face. Regulator 11 is provided with an inlet fitting 14 which communicates through a suitable conduit 15 with a source of gaseous oxygen contained in a bottle 16 car fective to deliver oxygen from bottle 16 to mask 10 in response to the aviators breathing.

Referring now to Fig. 2 wherein the details of construction and arrangement of regulator 11 are shown, casing 12 includes a substantially hollow cylindrical body 18 having a wall 19 disposed across one end while they opposite, or open end thereof is closed, by a cap, or cover 20 having a cylindrical side wall 21 that is adapted.

to mate with the open end of body 18. Cover 20 is removably secured to body 18 by suitable fastening means such as bolts 22 (Fig. 4).

to body 18 the mating edges of ,body 18 and side wall 21 of cover 20 cooperate to clampingly secure therebetween the,

peripheral portion of a flexible diaphragm 23.

Diaphragm 23 serves to divide the interior of casing 12 into a first chamber 24 defined by body 18, Wall 19 and diaphragm 23 and a second chamber 25 defined by cover 20, the side wall 21 thereof and diaphragm 23. Chamber 24 communicates by way of suitable ports, or openings 26 formed in end wall 19 with the interior of mask 10, while chamber 25 communicates with atmosphere through a suitable opening 27 formed in end wall 21 of cover 20. Therefore, diaphragm 23 serves asa common wall between chambers 24 and 25 and since these chambers communicate with the interior of mask- 10 and ambient atmosphere, respectively, it is manifest that diaphragm 23 is moved in response to a pressure differential produced between chambers 24 and 25 by the. respiration of the aviator wearing mask 10. Thus, upon! When cover 20 is secured an exhalation by the aviator, the pressure in chamber 24 rises to a value above that of the ambient atmospheric pressure in chamber anddiaphragm 23 moves outwardly or in the direction of cover 20. Conversely, upon an inhalation by the aviator the pressure in chamber 24' is reduced to a value below that in chamber 25 and diaphragm 23, therefore, moves inwardly of chamber 24 in the direction of end wall 19.

Chamber 24 also communicates through a tubular member 28 mounted through end wall 19 with a chamber 29 formed in end wall 19. Chamber 29 is closed to the interior of mask 10 by a plate '30 that is secured at its peripheral portion toend wall 19 by suitable fastening means, not shown. Chamber 29. in turn,. communicates with the exterior of casing 12 through a slot 31 formed through regulator body 18. Thus, a passageway between chamber 24 and the exterior of casing 12 is provided comprising member 28,.chamber 29 and slot 31.

Communication between chamber 24 and the exterior of casing 12 through the aforenoted passageway is controlled by a vent valve assembly generally indicated by the reference character 32. To form vent valve assembly 32, tube 28 is extended partially into chamber 24 and the end of tube 28 disposed therein is provided with an annular valve seat 33. A valve disc 34 is biased into a sealing engagement with valve seat 33 by a spring 35 that is operatively positioned between the upstream side of disc 34 and a bearing plate 36 that is suitably secured to the central portion of diaphragm 23. Valve disc 34 has a greater diameter than its coacting valve seat 33 to the end that th: edge of disc 34 extends outwardly beyond the limits of seat 33. A plurality of fingers 37, having inwardly disposed lateral flanges 38 and 39 at the oposite ends thereof are secured by flanges 38 to bearing plate 36. Fingers 37 are disposed so that the flanges 39 thereof are engageable with the edge of disc 34 at the downstream side thereof. Moreover, the length of each finger 37 is such that when diaphragm 23 is in a null position as shown in Fig. 2, lateral flanges 39 are slightly spaced from and out of contact with disc 34 to the end that spring 35 is free to engage disc 34 with its coacting seat 33 to close communication through member 28.

Due to the foregoing construction and arrangement of parts, when diaphragm 23 is actuated to move outwardly, i. e., in the direction of cover 20, lateral flanges 39 of fingers 37, engage disc 34 and lift the same off its coacting seat 33 against the bias of spring 35 thus opening chamber 29 to chamber 24 and communicating the latter through chamber 29 and tube 28 with the exterior of casing 12. On the other hand, an inward movement of diaphragm 23 from a null position causes lateral flanges 39 to move further away from disc 34 and at the same time spring 35 is further compressed to increase the sealing engagement of disc 34 with its coacting seat 33.

As hereinbefore set forth, gaseous oxygen is supplied from bottle 16 through conduit 15 to inlet fitting 14 of regulator 11. Inlet 14 includes an inlet pipe 40 to which conduit 15 is connected and a mounting flange 41 formed thereon is secured to body 18 by suitable means, not shown. Flange 41 serves to close the outer end of an opening 41a formed in body 18 and which communicates at the inner end thereof with chamber 24.

Demand valve means 42 are provided to control the flow of oxygen through inlet fitting 14 into chamber 24. To that end, pipe 40 is extended partially into opening 41a and a section of resilient tubing 43, made of soft.

rubber or a like material, is sealingly secured thereto so as to form a continuation of pipe 40 that extends partially into chamber 24. A support block 44, mounted to the inner side of flange 41 by bolts 45 (Fig. 4) has fixedly secured to one side thereof by pins 46, a member 47 having a laterally disposed clamping jaw 48. A lever 49, pivotally mounted at one end by a pin to the oppositesideof block 44 is also provided with a clamping jaw 51. Fixed and movable jaws 48 and 51, respectively, are disposed relative to each other and to tube 43 so as to be engageable with tube 43 on diametrically opposite sides thereof and medially of its length. Lever 49 extends into chamber 24 and a spring 52 operatively positioned between end wall 19 and a U-shaped recess 53 formed on lever 49 biases the latter in a direction whereby jaw 51 is moved toward jaw 48 to the end that tube 43 is clamped therebetween to close the same and prevent oxygen from entering chamber 24. The inner, or free end 54 of lever 49 is engaged with a lateral flange 39 of one of the fingers 37. It is noted, that when jaws 51 and 48 are cooperating to close tube 43, end 54 of lever 49 contacts flange 39 but there is no load transmitted from spring 52 through lever 49 to finger 37.

As shown in Figs. 5 and 6, cover 20 has formed thereon a pair of spaced, outstanding lugs 55 that are disposed on either side of opening 27 which carry a pivot pin 56. Primary and secondary levers 57 and 58 are mounted, adjacent to the outer end thereof, for independent pivotal movement about pin 56 and extend through opening 27 into cover 20. To accommodate this mounting and pivotal movement of levers 57 and 58, the latter is pro vided with a rectangular opening 59.

A pair of tension springs 60 secured at one end to a transverse pin 61 carried by the outer end of secondary lever 58 extend through opening 27 and across the interior cf cover 20 where the opposite ends thereof are secured to adjustment members 62. Each adjustment member 62 comprises a bolt 63 rotatably mounted through side wall 21 and a nut 64 to which springs 60 are secured. By rotating bolt 63 in the proper direction, nut 64 is moved on bolt 63 so as to adjust the tension of springs 69. Springs 60 tend to pivot lever 58 about pin 56 in' a direction whereby the inner end of lever 58 engages a second bearing plate 65 secured to the central portion of diaphragm 23.

To prevent the aforenoted pivotal movement of lever 58 until such time as it is desired, the inner end of lever 58 is constructed and arranged to engage an arm 66 of a bellcrank 67. More particularly, the inner end of lever 58 is first bent at right angles to the length of lever 58 to form a transverse portion 68 and then bent at right angles to portion 68 to form a lateral extension 69 that engages the outer end of arm 66 of bellcrank 67. Bellcrank 67 is mounted for pivotal movement about a pin 70 that is carried in a pair of spaced brackets 71. Brackets 71 are secured by rivets 72 to the inner side of cover 20. Adjacent the outer end thereof, arm 66 is provided with a right angle extension 73, and a spring wire 74 carried by brackets 71 engages arm 66 at the point where extension 73 is joined thereto. Spring 74 biases bellcrank 67 in a clockwise direction, as shown in Fig. 2, to the end that the outer end of arm 66 is maintained in engagement with the end of extension 69.

Cover 20 has also mounted therein a leaf spring 75 that is secured at one end by a rivet 75a to the inner sur-. face of cover 20. At the other end thereof, spring 75 engages and supports a cap or button 76 that extends partially through an opening 77 formed in cover 20, to the exterior of said cover. An aneroid 78 mounted on button 76 is positioned within cover 20 so as to have the end plate 79 thereof adjacent to and engageable with arm 80 of bellcrank 67.

Primary lever 57 is provided adjacent its outer end with a U-shaped bracket 81 which carries a transverse pin 82. A tension spring 83 secured at one of its ends to pin 82 extends through opening 27 into cover 20 where the opposite end thereof passes through a slot formed in transverse portion 68 and extension 69 of lever 58 and engages with a cross pin 85. Cross pin 85 is held in engagement with transverse portion 68 of lever 58 by the tension of spring 83. Spring 83 serves to bias, primary lever 57 in a direction whereby the free end 86 thereof engages bearing plate 65 of diaphragm 23.

to the free end 54 of lever 49 of the demand valve.

As hereinbefore set forth, regulator 11 is provided with a lever 17 which is operable in one position to permit the ambient air to be delivered to mask 10, while a second position of lever 17 adjusts regulator 11 to the end that oxygen is delivered to mask 10. More particularly, as shown in Figs. 2 and 4, a sleeve 87 having a flange 88 is secured by flange 88 to body 18 by bolts 89. Sleeve 87 extends through a suitable opening in body 18 into chamber 24. A shaft 90, rotatably supported in sleeve 87, has secured thereto at its outer end lever 17, while at the inner end thereof it is provided with a laterally disposed arm 91 that is engageable with plate 36 when the former is moved-to a position normal to the latter by lever 17. A spring 92 encircling shaft 90 and operative between a washer 93 on shaft 90 which abuts arm 91 and the inner end of sleeve 87 biases shaft 90 in a direction to draw lever 17 into engagement with a resilient washer 94 that is interposed between the adjacent surfaces of flange 88 and lever 17. Due to this construction and arrangement, washer 94 serves to seal any leakage along shaft 90 between chamber 24 to the exterior of casing 12. Moreover, lever 17 is drawn in frictional engagement with washer 94 to the end that lever 17 will remain in a fixed position relative to washer 94 until manually moved therefrom.

Regulator body 18 has also formed therein a chamber 95 into which is mounted a microphone 96. Suitable electrical leads 97 pass through a fitting 98 secured to body 18 and are connected to microphone 96.

Having described the details of construction and arrangement of parts of the novel regulator contemplated herein, the operation of the device is as follows.

At low altitudes, e. g., below 10,000 feet, where the ambient air contains a sufiicient supply of oxygen to permit normal human etficiency, lever 17 is turned to move shaft 90 and hence arm 91 to a position where the latter is normal to bearing plate 36. This movement of arm 91 moves bearing plate 36 and hence diaphragm 23 outwardly, i. e., in the direction of cover 20 against the bias of primary lever 57. Upon the outward movement of diaphragm 23, fingers 37 also move outwardly and out of contact with the free end 54 of lever 49 thereby permitting spring 52 to maintain demand valve 42 closed, while flanges 39 engage and raise disc 34 off its coacting seat 33 to open vent valve 32. Chamber 24 is thereby placed in communication with the exterior of regulator 11 through tube member 28, chamber 29 and slot 31. Therefore, in response to the respiration of the aviator wearing mask 18, ambient air is drawn into mask 10, and the exhalation of the aviator is exhausted therefrom through the passageway defined by slot 31, chamber 29, member 28, chamber 24 and ports 26. During respiration, arm 91 serves to maintain diaphragm 23 in the outwardly disposed or inactive position thereof to the end that demand valve 42 remains closed and vent valve 32 remains open.

When the aviator reaches an altitude where oxygen is required to maintain normal efficiency, i. e., above 10,000. feet, lever 17 is turned manually to the position shown in Fig. 4. This turning of lever 17 is transmitted through shaft 90 to arm 91 and the latter is moved to a position parallel to diaphragm 23, as shown in Figs. 2 and 4. As arm 91 is disengaged from plate 36, diaphragm 23 moves inwardly in the direction of wall 19 and fingers 37 also move inwardly thereby permitting spring 35 to seat disc 34 on valve seat 33 to the end that vent valve 32 is closed and chamber 24 is closed to the exterior of regulator 11.

Primary lever 57 and spring 83 cooperate to place a load upon diaphragm 23 that is transmitted through fingers 37 Due to this loading, lever 49 is moved and movable jaw 51 carried thereby moves away from fixed jaw 48 to permit a relatively slight flow of oxygen through inlet 40 and tube 43 into chamber 24. As the oxygen enters chamber 24, the pressure thereof becomes effective on diaphragm 23 to move the same outwardly against the bias of pri-.

on diaphragm 23 to produce a force that balances the force imposed thereon by primary lever 57. At this time, tube 43 is clamped between jaws 51 and 48 to prevent flow through tube 43. Thus, primary lever 57 serves to maintain a positive or safety pressure within chamber 24 and mask 10 of about .25 inch of water, to the end that any leakage between mask 10 and the face of the aviator wearing the same is outwardly into the ambient atmosphere. This outward leakage prevents the dilution of the oxygen'within mask 10.

The description hereinbefore set forth, relates to the operation of regulator 11 during the pause between an inhalation and exhalation of the aviator. Upon an inhalation, the suction produced thereby in mask 10 and chamber 24 moves diaphragm 23 inwardly of chamber 24. This inward movement of diaphragm 23 and fingers 37 secured thereto pivots lever 49 against the bias of spring 52 and moves jaw 51 away from jaw 48. Tube 43 opens and oxygen flows into chamber 24 and from thence through ports 26 into mask 10 and the aviators lungs. It is also noted, the inward movement of diaphragm 23 increases the bias of spring 35 on disc 34 so that a positive sealing engagement between disc 34 and its coacting seat 32 is assured.

Upon exhalation, diaphragm 23 moves outwardly into cover 20 in response to the increase of pressure within chamber 24 due to the exhalation. portion of the outward movement of diaphragm 23 and fingers 37, spring 52 moves lever 49 to clamp tube 43 between jaws 51 and 48 to cut off the flow of oxygen into chamber 24. As fingers 37 continue to move outwardly with diaphragm 23, flanges 39 first engage disc 34 and then lift the same off its coacting seat 33 to permit the exhalation to pass through member 28, chamber 29 and slot 31 to atmosphere.

The operation of regulator 11 hereinbefore set forth, assures the delivery of a sufficient quantity of oxygen to the aviator up to an altitude of about 40,000 feet. Above this altitude it is necessary to supply the aviator with oxygen under a pressure sufiiciently high to force the oxygen into his lungs. The present regulator operates to accomplish the end as follows. During ascent, to high altitude, aneroid 78 expands in response to the decrease in ambient atmospheric pressure. The expansion of aneroid 78 is adjusted to the end that at slightly below an altitude of 40,000 feet, end plate 79 of bellows 78 engages arm 80 of bellcrank 67 and begins to rotate the same in a counterclockwise direction as shown in Fig. 2 against the bias of spring 74. At an altitude of about 40,000 feet, aneroid 78 will have rotated bellcrank 67 to a point where arm 66 thereof disengages from extension 69 of secondary lever 58. Secondary lever 58 is then pivoted by springs 60 and engages bearing plate 65 of diaphragm 23. Thus, at this time, both primary lever 57 and secondary lever 58 are engaged with plate 65 and impose a bias through their respective springs 83 and 60 on diaphragm 23 that moves the latter inwardly of chamber 24. The inward movement of diaphragm 23 and fingers 37 pivots lever 49 against the bias of spring 52 to move jaw Slaway from water is maintained'in chamber 24 and hence mask m During the initial It is manifest, therefore, that when the aviator inhales, the oxygen supplied to mask is forced into the lungs of the aviator. Upon exhalation, regulator 11 operates as aforesaid to open valve 32 and permit the exhalation to vent through member 28, chamber 29 and slot 31 to atmosphere.

In the event the aviator descends into a lower altitude where pressure breathing is no longer required, aneroid 78 contracts in response to the ambient atmospheric pressure at the lower altitude. As aneroid 78 contracts, spring 74 rotates bellcrank 67 to the position shown in Fig. 2. Secondary lever 58 is reengaged manually with arm 66 of bellcrank 67 by the aviator pressing, or pushing on the outer end 58a of lever 58 so as to rotate the same against the bias of springs 60. As lever 58 rotates in this direction, the lateral extension 69 thereof engages arm 66 and rotates the same in a clockwise direction, as shown in Fig. 2, against the bias of spring 74. When extension 69 clears the end of arm 66, spring 74 moves the latter in a counterclockwise direction until such rotation is arrested by extension 73, at which time arm 66 is in engagement with extension 69 of lever 58 to lock the latter in the position shown in Fig. 2.

As hereinbefore set forth, aneroid 78 is resiliently supported in cover by a leaf spring 75 and button 76, to which aneroid 78 is secured, extends to the exterior of cover 20. Therefore, in the event the aviator desires to set the regulator for pressure breathing manually, he merely presses on button 76 to move it inwardly of cover 20 against the bias of leaf spring 75. The resulting inward movement of aneroid 78 engages the bottom plate 79 thereof with arm 80 of bellcrank 67 and moves the same to disengage arm 66 from extension 69 of lever 58. Lever 58 is then released to rotate in response to the bias of springs 61 to a position where it engages bearing plate 65 of diaphragm 23. Regulator 11 will then operate, as hereinbefore set forth, to maintain the pressure of the oxygen in chamber 24 and hence mask 10 at a value of 15 inches of water.

Having thus described the details of construction and operation of the novel oxygen demand regulator contemplated herein, it will be apparent to one skilled in the art that the various objects of the instant invention hereinbefore set forth have been achieved.

Moreover, while only one embodiment of the novel demand regulator has been illustrated and described, various changes in the form and arrangement of the various elements which will now be apparent to those skilled in the art, may be made without departing from the scope of the invention.

What is claimed is:

1. An oxygen demand regulator adapted to be mounted to and form a part of a breathing mask, said regulator including a breathing chamber communicating with the mask, a respiratory responsive diaphragm in said chamber, an inlet to said chamber, a demand valve controlling flow through said inlet into said chamber, said demand valve including a resilient tube extending partially into said chamber, a fixed jaw engageable with one side ofv said tube, a movable jaw engageable with the opposite side of said tube, a lever'for moving said movable jaw relative to said fixed jaw to engage said tube therebetween and thereby control flow through said tube, means biasing said lever in a direction whereby said tube is clamped between said jaws to close fiowthrough said tube, a passageway communicating said chamber to-the exterior of said regulator, a vent valve controlling flow through said passageway, said vent valve including a valve seat, a valve disc engageable with said valve seat, resilient means biasing said disc into engagement with said seat, and one or more fingers carried by said diaphragm and engageable with said valve disc, at least one of. said fingers engageable with said lever whereby movement of said diaphragm in one direction engages said one finger with said lever and actuates said lever to move said movable jaw away from said fixed jaw to permit flow throughsaid tube, and movement of said diaphragm in a second direction engages said fingers with said valve disc to disengage said valve disc from said valve seat to thereby communicate said chamber through said passageway with the exterior of said casing.

2. An oxygen demand regulator adapted to be mounted to and form a part of a breathing mask, said regulator including a breathing chamber communicating with the mask, a. respiratory responsive diaphragm in said chamber, an inlet tosaid chamber, a demand valve controlling fiow through said inlet into said chamber, said demand valve including a resilient tube extending partially into said: chamber, a fixed jaw engageable with one side of said tube, a movable jaw engageable with the opposite side of said tube, a lever for moving said movable jaw relativeto said fixed jaw to engage said tube therebetween and thereby control flow through said tube, means biasing said lever in a direction whereby said tube is clamped between said jaws to close flow through said tube, and means for operatively engaging said lever with said diaphragm whereby movement of said diaphragm in one direction actuates said lever to move said movable jaw away from said fixed jaw to thereby permit flow through said tube into said chamber.

3. An oxygen demand regulator adapted to be mounted to and form a part of a breathing mask, said regulator including a breathing chamber communicating with the mask, arespiratory responsive diaphragm in said chamber, an inletto said chamber, a demand valve controlling flow through said inlet into said chamber, said demand valve including a resilient tube extending partially into said chamber, a fixed jaw engageable with one side of said tube, a movable jaw engageable with the opposite side of said tube, a lever for moving said movable jaw relative to said fixed jaw to engage said tube therebetween and thereby control flow through said tube, means biasing said lever in a direction whereby said tube is clamped between said jaws to close flow through said tube, means for operatively engaging said lever with said diaphragm whereby movement of said diaphragm in one direction actuates said lever to move said movable jaw away from said fixed jaw to thereby permit flow through said tube into said chamber, and normally closed vent means communicating said chamber to the exterior of said regulator and operable by said engaging means whereby movement of said diaphragm in a second direction opens said vent means.

4. An oxygen demand regulator adapted to be mounted to and form a part of a breathing mask, said regulator including a breathing chamber communicating with the mask,.a respiratory responsive diaphragm in said chamber, an inlet to said chamber, a demand valve control ling flow through said inlet into said chamber, said demand valve including a resilient tube terminating in said chamber, a fixed jaw engageable with one side of said tube, a movable jaw engageable with the opposite side of said tube, a lever for moving said movable jaw relative to said fixed jaw to engage said tube therebetween and thereby control flow through said tube, means biasing said lever in a direction whereby said tube is clamped between said jaws to close flow through said tube, means for operatively engaging said lever with said diaphragm whereby movement of said diaphragm in one direction actuates said lever to move said movable jaw away from said fixed jaw to thereby permit flow through said tube into said chamber, normally closed vent means communicating said chamber to the exterior of said regulator and operable by said engaging means whereby movement of said diaphragm in a second direction opens said vent means, and means for moving said diaphragm in said second direction to a predetermined position where said vent means are opened and maintaining said diaphragm in said predetermined position.

5. In an oxygen demand regulator having a casing for connection to a breathing mask, the combination comprising a breathing chamber in said casing, a demand valve controlling the flow of pressurized oxygen into said chamber, a respiratory responsive diaphragm controlling the operation of said demand valve, a pivot pin carried by said casing, a primary lever pivotally mounted at one end on said pivot pin and engageable at the opposite end thereof with said diaphragm, means biasing said primary lever to pivot on said pin whereby the opposite end of said primary lever normally engages said diaphragm and imposes a first predetermined force thereon to thereby actuate said demand valve to maintain a first predetermined pressure of oxygen in said chamber, a secondary lever pivotally mounted at one end on said pivot pin and engageable at the other end thereof with said diaphragm, means biasing said secondary lever for pivotal movement on said pin whereby the opposite end of said secondary lever engages said diaphragm, latching means engageable with said other end of said secondary lever to prevent the pivotal movement thereof, and altitude responsive means engageable with said latching means for releasing said secondary lever from said latching means at a predetermined altitude whereby said secondary lever is pivoted by its biasing means to engage said diaphragm, said primary and secondary levers being effective to impose a second predetermined force on said diaphragm to thereby actuate said demand valve to maintain a second predetermined pressure of oxygen in said chamber.

6. In an oxygen demand regulator having a casing for connection to a breathing mask, the combination comprising a breathing chamber in said casing, a demand valve controlling the flow of pressurized oxygen into said chamber, a respiratory responsive diaphragm controlling the operation of said demand valve, a pivot pin carried by said casing, a pair of levers, each of said levers mounted at one end to said pin and engageable at its opposite end with said diaphragm, resilient means individual to each lever and biasing its lever to pivot on said pin to engage the opposite end thereof with said diaphragm and impose a predetermined force thereon, one of said levers normally engaging said diaphragm and effective to impose a predetermined force thereon whereby said diaphragm operates said demand valve to maintain a first predetermined pressure of oxygen in said chamber, and altitude responsive means engageable with the other lever, said altitude responsive means normally operative to hold said other lever out of engagement with said diaphragm at altitudes below a predetermined altitude and to release said other lever for engagement with said diaphragm at said predetermined altitude, said other lever being effective upon engagement with said diaphragm to increase the predetermined force imposed thereon to a second predetermined force whereby said diaphragm operates said demand valve to maintain a second predetermined pressure of oxygen in said chamber.

7. In an oxygen demand regulator having a casing for connection to a breathing mask, the combination comprising a breathing chamber in said casing, a demand valve controlling the flow of pressurized oxygen into said chamber, a respiratory responsive diaphragm controlling the operation of said demand valve, a pivot pin carried by said casing, a pair of levers, each of said levers mounts ed at one end on said pin and engageable at its opposite end with said diaphragm, resilient means individual to each lever and biasing its lever to pivot on said pin to engage the opposite end thereof with said diaphragm and impose a predetermined force thereon, one of said levers normally engaging said diaphragm and effective to impose a predetermined force thereon whereby said diaphragm operate-s said demand valve to maintain a first predetermined pressure of oxygen in said chamber, and altitude responsive means engageable with the other lever, said altitude responsive means normally operative to hold said other lever out of engagement with said diaphragm at altitudes below a predetermined altitude and to release said other lever for engagement with said diaphragm at said predetermined altitude, said other lever being effective upon engagement with said diaphragm to increase the predetermined force imposed thereon to a second predetermined force whereby said diaphragm operates said demand valve to maintain a second predetermined pressure of oxygen in said chamber, and manually operable means for actuating said altitude responsive means to release said other lever.

8. In an oxygen demand regulator, the combination comprising a chamber, an oxygen inlet to said chamber, inlet valve means controlling flow through said inlet into said chamber, a respiratory responsive diaphragm in said chamber, vent means communicating said chamber to atmosphere, means carried by said diaphragm and engageable with said inlet valve and vent means to alternately open and close said inlet valve and vent means in response to respiration-s, resilient means biasing said diaphragm to actuate said inlet valve and vent means to maintain a predetermined pressure of oxygen in said chamber, second resilient means engageable with said diaphragm to bias the same in conjunction with said first resilient means to actuate said inlet valve and vent means to maintain a second predetermined pressure of oxygen in said chamber, and means engageable with said diaphragm and operable to move said diaphragm against the bias of said first and second resilient means to a position whereby said inlet valve means close and said vent means open to thereby vent said chamber to atmosphere.

9. An oxygen demand regulator comprising a breathing chamber having an oxygen inlet, a demand valve at the inlet controlling the flow of oxygen into said chamber, a vent valve, a respiration responsive diaphragm in the chamber, means carried by said diaphragm and operated thereby to alternately open and close said demand valve and vent valve, means for biasing the diaphragm in a direction to open the demand valve, and means including an aneroid for rendering the biasing means operative when the regulator is at not less than a predetermined altitude.

References Cited in the file of this patent UNITED STATES PATENTS 1,131,490 Drager Mar. 9, 1915 1,926,069 Sutton Sept. 12, 1933 2,384,669 Fields Sept. 11, 1945 2,583,502 Wiggins Jan. 22, 1952 2,597,039 Seeler May 20, 1952 2,598,525 Fox May 27, 1952 

